Specifies provisions for evaluating the severity of in-situ, broad-band shaft vibration measured radial (i.e. transverse) to the shaft axis at, or close to, the main bearings. These are in terms of: - vibration under normal steady-state operating conditions; - vibration during other (non-steady-state) conditions when transient changes are taking place, including run up or run down, initial loading and load changes; - changes in vibration which can occur during normal steady-state operation.